1. Field of the Invention
The present invention relates to an automatic transfer apparatus for a liquid crystal display (LCD) device and a method for sensing obstacle using the same, and particularly, to an automatic transfer apparatus for an LCD device which is capable of preventing a damage on a structure of an automatic transfer apparatus due to an obstacle by mounting a sensing member which is mounted at a bottom surface of the automatic transfer apparatus to sense the obstacle on the bottom, and by previously checking an existence of the obstacle.
2. Background of the Invention
Development of information society has gradually enhanced requirements for various types of display devices. Among various types of flat panel display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), electro luminescent displays (ELDs), field emission displays (FEDs), and the like LCDs are spotlighted the most to continue be developed as monitors for TV sets and desktop computers as well as monitors for notebook computers.
The LCD device may broadly be divided into LCD panels for displaying images and a driving unit for applying a driving signal to the LCD panels.
As shown in FIG. 1, a related art LCD panel includes first and second substrates 1 and 2 which are bonded to each other with a certain space therebetween, and a liquid crystal layer 3 injected between the first and second substrates 1 and 2.
Here, the first substrate 1 (i.e., a thin film transistor (TFT) array substrate) includes a plurality of gate lines 4 arranged in one direction by a certain interval therebetween, a plurality of data lines 5 arranged by a certain interval therebetween in a direction perpendicular to each gate line 4, a plurality of pixel electrodes P formed in a matrix shape at each pixel region defined at an intersection between the gate lines 4 and the data lines 5, and a plurality of TFTs which are switched by a signal from the gate line 4 to transfer a signal from the data line 5 to each pixel electrode P.
Furthermore, the second substrate 2 (i.e., a color filter substrate) includes a black matrix layer 7 for preventing light from being transmitted to regions rather than the pixel regions, R, G and B color filter layers 8 for rendering color and a common electrode 9 for implementing images. Here, the common electrode 9 may be formed on the first substrate 1 in an LCD device employing a horizontal electric field mode.
The LCD device having such structure is fabricated by processes for fabricating a TFT array on the first substrate 1, fabricating a color filter layer on the second substrate 2, bonding the first and second substrates 1 and 2 to each other, injecting a liquid crystal between the bonded substrates 1 and 2 and sealing the liquid crystal, testing and repairing each LCD panel in which the liquid crystal has been injected, and mounting a back light or the like in each LCD panel with a good quality and mounting a driving circuit to fabricate a liquid crystal display module.
The substrates undergoes such various processes to completely be the LCD device. The substrates are transferred to devices which perform each process by use of an automatic transfer apparatus.
With reference to FIGS. 2 and 3, explanation will now be given for a related art automatic transfer apparatus used to transfer the substrates to the devices for performing each process upon fabricating an LCD device.
FIG. 2 is a schematic view showing a related art automatic transfer apparatus having a cassette.
FIG. 3 is a schematic view showing the related art automatic transfer apparatus having the cassette, which shows a case that there is an obstacle on a movement direction.
Referring to FIG. 2, a related art automatic transfer apparatus 10 includes a mounting unit 15 for placing a cassette 31 in which a plurality of substrates are received in order to perform each process, and a moving unit 11 disposed at a bottom of the mounting unit 15 and moving within a designated interval, namely, moving toward each processing device by use of rotational movement members 13. A distance T1 is a height between the outer bottom surface 41 and the lower portion of the moving unit 11. The mounting unit 15 of the automatic transfer apparatus 10 has a robot arm 21 which is used to load the cassette 31 which is positioned at an input port (not shown) and an output port (not shown) of a stoker (not shown) directly on the mounting unit 15 or to unload the cassette 31 which has been loaded on the mounting unit 15 to the stoker.
In a state that the automatic transfer apparatus 10 is moved toward each processing device in order to perform each process, the cassette 31 which has been loaded on the mounting unit 15 by the robot arm 21 or the cassette which is placed at the input port or output port is moved to each processing device or to the stoker.
However, as shown in FIG. 3, it is impossible for the automatic transfer apparatus 10 according to the related art to sense an obstacle 51 on the bottom out of the range in which a front of the obstacle 51 can be sensed. Here, T2 is a thickness of the obstacle 51.
Therefore, impurities come into the bottom of the automatic transfer apparatus 10, which causes interference with a lower structure of the automatic transfer apparatus 10, resulting in problems in devices. That is, when an obstacle which is not sensed at a bottom of a movement detecting sensor or the moving unit is sucked into the bottom of the automatic transfer apparatus, damages may occur on the bottom structure of the automatic transfer apparatus.